1. Field of the Invention
The invention relates generally to the field of photography, and in particular to a film cassette containing a film roll. More specifically, the invention relates to a film cassette that is capable of advancing a filmstrip including a non-protruding leader portion out of the cassette shell when a spool core about which the filmstrip is coiled is rotated in an unwinding direction.
2. Description of the Prior Art
Commonly assigned U.S. Pats. No. 5,151,730, issued Sep.29, 1992, No. 5,040,739, issued Aug. 20, 1991, and No. 5,151,730, issued Feb. 15, 1991, disclose a film cassette that is capable of advancing a filmstrip including a non-protruding leader portion out of the cassette shell. As can be seen from a reading of the patents, the film cassette includes a spool core supported inside the cassette shell for rotation in an unwinding direction to advance a filmstrip coiled about the spool core out of the cassette shell and in a winding direction to draw the filmstrip into the cassette shell, and a pair of flexible flanges coaxially arranged along the spool core to overlie opposite sides of the film roll to radially confine the film roll within skirted peripheries or annular lips of the flanges. The two flanges have respective central openings through which the spool core coaxially extends to permit the flanges and the spool core to be independently rotated in the two directions. A film stripper projects from the cassette shell to be received underneath a leading end of the leader portion when the spool core is rotated in the unwinding direction, to free the leader portion from the radial confinement of the flanges by inducing the leader portion to flex the flanges slightly away from each other at their skirted peripheries. Several engagement hooks are fixed to the spool core for rotation with the spool core relative to the flanges, to move into engagement with at least one of the flanges when the spool core is rotated in the unwinding direction, to make the engaged flange(s) rotate in unity with the spool core in the unwinding direction, and for movement out of engagement with the engaged flange(s) when the spool core is rotated in the winding direction, to permit the flanges and the spool core to be independently rotated in the winding direction.
It has been recognized that by fixing at least one of the flanges to the spool core during unwinding rotation of the spool core, as contrasted with allowing the flanges and the spool core to be independently rotated in the unwinding direction as in commonly assigned U.S. Pat. Nos. 4,834,306 and 4,848,693, there is immediately affected a frictional relationship between the outermost convolution of the film roll and the skirted periphery(s) of the engaged flange(s) which improves the ability of the spool core to the cassette shell. In particular, the frictional relationship increases the pushing force necessary to thrust the leader portion out of the cassette shell.